A magnet generator type ignition device has been extensively adopted for such internal combustion engines as, for example, chain saws and special vehicles. Such devices provide an electric source of high voltage current not from a battery but from a magnet generator wherein the low voltage current generated by the magnet generator is made high in voltage by an ignition coil and fed to the spark plugs.
For constant high speed operation of such engines the ignition time in the engine is advantageously set near 30 degrees before the top dead center so that the combustion efficiency of the gaseous mixture may be maximized. However, when the speed rotation of the internal combustion engine is low as at the time of starting the engine, the same timing as mentioned above is disadvantageous since the engine will tend to reversely rotate making the starting difficult. That is to say, problems have arisen when the rotation speed of the internal combustion engine is low, if the ignition occurs within 30 degrees before the top dead center, because the piston will lower before it reaches the top dead center causing a push-back force reversely rotating the internal combustion engine.